The purpose of this field project is to evaluate the impact of a combinant water-sanitation intervention on the occurrence of pediatric diarrhea and other targeted outcomes in a study population residing in the Assiut governorate of Upper Egypt. 20 villages, which together included a population of approximately 10,000 persons, were randomly assigned to receive the intervention (N=10) or no intervention (N=10). The intervention consisted of provision of India Mark II tubewells and household latrines, together with an educational package stressing personal hygiene and water behaviors. To assess the impact of the intervention, all families in these villages were followed with longitudinal surveillance during a one-year follow-up period. Outcomes of interest included observed water-sanitation behaviors, environmental cleanliness, water microbiological quality, and, as the primary outcome, the occurrence of diarrhea in children under 3 years of age. The intervention was implemented during late 1990, and follow-up continued through 1991. Data from the project have now been entered into computerized media, and final data editing is now in progress. Preliminary analyses indicate that the intervention was successful in reducing the rate of pediatric diarrhea by 17%, and that this effect included both watery and non-watery diarrheas, as well as both acute and persistent diarrheas. Analyses of the trial will continue in FY 93.